Manufacture of center stretched strip



g- 1943- v L. L. WILSON ETAL 2,326,715

MANUFACTURE OF CENTER STRETCHED STRIPS Filed Feb. 15, 1941 2sheets-Sheet 1 L10 d L. Wilson 114m .Qflazwelll, flibla d W lea millerPatented Aug. 10, 1943 CENTER s'rnn'ronnn s'rm Lloyd L. Wilson,Sharpsville, and Harold W; Lowmiller, Farrell, Pa, and Maxwell L. Bible,Masury, Ohio, assignors to Sharon Steel Cora "MANUFACTURE OF :poration,Sharon, Pa.,

sylvania a corporation at Penn- Application February 13, 1941, SerialNo, 378328 10 Claims.

The invention relates to the manufacture of thin, flexible strip havingsufficient stifiness and resiliency to snap backer restore itself to itsoriginal position when flexed. s

More particularly, the invention relates to the manufacture of thinflexible metal strip adapted to maintain itself in a longitudinallystraight condition when supported over a relatively long span, and torestore itself to said straight condition when bumped or otherwiseflexed between pports.

One example of \a use for such strip is the slats in Venetian blinds,wherein slats of thin metal strip are supported over a span ofapproximately thirty-three inches, and may be curved or bent laterallyto a desired shape but are required to be normally straightlongitudinally and to snap back or return themselves to said straightcondition when flexed or bumped.

It has been found thata Venetian blind slat of A further object is toprovide a novel method of continuously roller stretching the center of athin metal strip longitudinally,

Likewise, it is an object of the present invention to provide a methodof providing a center stretch in thin strip material without producingany permanent longitudinal bow in the material.

Another object is to provide a novel apparatus for continuously centerstretching a strip longi tudinally thereof without requiring the use of.

drawing dies.

A. further object is to provide a novel arrangement of convex'rolls forcenter stretching a metal strip when passed successively thereover toproduce a longitudinally straight and flat strip which may thereafter belaterally curved to have such stifines and. rigidity as to maintainitself in straight condition, and to restore itself to such thin metalstrip made according to conventional practice hasa definitetendency tosag or bend longitudinally between supports, and when curved laterallyby forming between mating convex and concave rolls, this longitudinalbending may ocour in the direction of the lateral curve in which case itis called down bow, or in theopposite direction in which case it iscalled back bow.,

It has been found also that the down bow and V back bow can. becontrolled by longitudinally stretching the center of the strip.prior'to the lateral forming operation to produce a slat which willmaintain itself in a straight condition longitudinally over a given spanof approximately tlnrty-three-inches, and-which when flexed will restoreitself or snap back to said straight condition.

Prior to our invention, the required longitudinal center stretchingofthe strip has been, accomplished by drawing a strip through draw blocksor dies prior to the lateral curving orforming operation. However, thisdrawing operationproduces scratches on the surface of the strip unlessthe drawing dies are carefully and thoroughly cleaned at frequentintervals, which adds materially to the time and expense of the centerstretching operation.

condition when flexed.

These and other objectsare attained by the novel method and apparatuscomprising the present invention, which is shown by way of example inthe accompanying drawings and hereinafter described in detail anddefined in the appended claims.

The present novel method may be stated in general terms as includingroller stretching the center of the continuous strip longitudinally bypulling the strip in a sinuous path past and in contact with one afteranother of a series of convex rolls, and wrapping the'strip around asubstantial portion of the periphery of certain of said rolls, whilemaintaining the tension on th strip substantially equal at all of therolls.

The present novel a paratus may be stated in general terms as includinga frame, a series of convex rolls jouinaleddn said frame, means forpulling a continuous strip in a sinuous path successively past and incontact with said rolls, cer tain of, said rolls being so located withrespect to other rolls as to cause th strip to wrap around a substantialportion of r theperiphery of said We have invented a novel method andapparatus for center stretching thin metal strip so as to eliminate theuse of drawing dies and their attendant disadvantages. i V a It istherefore an object of the present invention to provide a novel andeconomical method of producing a center stretched metal stripwithout-surface scratches.

certain rolls, and certain of said rolls being Journaled in bearingshaving floating mountings in the frame whereby the tensioned pull on thestripadjusts the location of said floating rolls with respect to otherof said rolls so that the tension on the strip is substantially equal atall of said rolls.

Referring to thedrawings forming part hereof,

Figure 1 is a diagrammatic view in longitudinal section of the novelapparatus for center stretching a continuous strip;

Fig. 2 is an enlarged cross sectional view of thestrip prior to itspassing through the edge rolls; Fig. 3 is a fragmentary sectional viewthrough the strip at the edge rolls;

Fig. 4 is an enlarged side elevation of the frame of the apparatus,showing the manner of sec- Fig. 8 is an enlarged sectional view as online- 8-8, Fig. 4.

Similar numerals refer to similar parts throughout the drawings.

Roll is is mounted substantially directly below roll I2 and is providedwith a vertically floating mounting. Preferably the end bearing plates29 for the roll l3 are provided with grooves 30 at their side edgesslidably engaging the'edge portions 25 of the'side plates l8 sothat theroll I3 is free to move up and down in the slot 23, itsa position beingdetermined by the amount of teneter and location of roll I 3 is such'asto directthe strip downwardly and rearwardly from A thin continuousstrip to be center stretched longitudinally is'indicated at 1, and maybe strip steel, although the invention may be applied to strips of othermaterials. The strip 1 is pulled through the improved center stretchingapparatus by means of a usual coiler or take-off reel indicateddiagrammatically at 1 8, for imposing a tensioned pull on the strip.

The novel center stretching apparatus is indicated generally at 9, andat the entrance side thereof combined centering, guide and edge rollsindicated at ID are provided for removing the sharp edges or burrs fromthe side edges of the strip and for centering and guiding the strip intothe stretching apparatus 9. These edging rolls preferably have taperedor V-shaped annular grooves lila into which the edge of the strip isentered for being edge rolled and guided.

Wipers 1017 may be interposed between the rolls l0 and stretchingapparatus 9 to remove dirt and dust from the strip and may be adjust-'ed for back tensioning the strip if desired.

As shown in Fig. 1 the center stretching appa ratus 9 includes aplurality of rolls ll, l2, 13, M, i5, i6 and I! over which the strip 1passes successively, and as shown in Figs. 5 to 8 inclusive, all ofthese rolls except i! have convexly curved peripheries or outerrollingsurfaces. Roll I1 is a cylindrical roll and has a fiat rollingsurface.

As shown, the rolls are journaled in side frame plates i8 and areirregularly staggered with respect to each other, so that the strip Tinpassing over and around and in contact with the rolls follows a sinuousand irregular path. Rolls H, H and i! are journaled in fixed bearingsI9, 28

and 2| respectively secured to the side plates l8 in a usual fashion.

Roll I2 is located above the level and forwardly of roll ii, and ispreferably journaled in end bearingplates 22 which are verticallyadjustable in the side plates l8. Preferably, the side plates l8 areslotted'vertically as indicated at 23 and i the bearing plates 22 areprovided with end grooves 24 slidably engaging the edge portions 25 ofside plates l8 defining the slotted opening 23'. Means-for verticallyadjusting the bearing plates 22 may include a transverse movable plate26 connecting the end bearing plates 22 and.

sion on the strip 1 which wraps around a portion of the periphery ofsaid roll l3. The diamroll l2.

Roll 14 is located in a position spaced from and forwardlyof roll l3for'directing the strip forwardly and slightly downwardly from roll l3.Roll I5 is provided with a horizontal floating mounting in the sideplates l8, and as shown the roll, [5 is located rearwardly of roll l4and above the same for directing the strip upwardly and rearwardly fromroll It. .The end bearing-plates 3| for the roll l5 are provided withgrooves 32 at their top and-bottom edges, which grooves slidably engagethe top and bottom edges 33 of a horizontal slot 34 formed in the sideplates l8, so that the roll l5 has a horizontal floating mountingsimilar to the vertical floating mounting of roll l3, its position beingdetermined by the tension on the strip lwvhich wraps around 4approximately half of the periphery of the roll.

Roll I6 is located forwardly of roll l5 for directing the stripdownwardly and forwardly from roll i5. Roll l6 preferably has ahorizontally adjustable mounting similar to the vertically adjustablemounting of roll I 2. The end bearing plates 35 for roll l6 preferablyare provided with grooves 36 at their top and bottom edges slidablyengagingthe top and bottom edges 33 of the side plates I8which definetheslot 34.

i8 and is connected to the end bearing plates 35, and an adjusting screw38 is rotatably secured at one end in the transverse plate 3'l-andthreaded through a fixed plate 49 extending transversely between andsecured to the ends of rthe side' tact with roll H and then upwardlyover and with its lower surface in contact with 'roll [2 and thendownwardly and rearwardly around and with its upper surface in contactwith roll [3.

The relative sizes and locations of rolls ll, I2

and [3 are such that the strip wraps around a substantial portion oftheperiphery of roll I 2,

said portion being approximately half of the periphery of said roll.

From under the floating-roll 13, the strip passes forwardly under andaround fixed roll M- with its upper surface in contact with a portion ofthe periphery thereof and thence upwardly and rearwardly to wrap aroundand over fl0atl ng.r01ll5 with its lower surface in contact with asubstantial portion thereof, and then downwardly and forwardly under andwith its upper surface in contact with roll l6, from which it passesunder and with its upper surface in'contact with cylindrical roll 11 andthence to the take off reel 8. The relative sizes and locations of rollsl4, l5. and I6 are such as to cause the strip to wrap around asubstantial portion of the periphery of floating roll l5, and in theillustrated positions of the rolls the strip wraps around slightly lessthan half of the periphery of floating roll '|5.-

The several rolls of the novel apparatus have A transverse movable plate31 extends between the side plates in the drawings, we have found thatbest results are obtained by making the rolls of the following specificdiameters (measured at center of roll face) and specific radii of convexcurvature:

Radius of Roll Diameter curvature Inches Inches 1. 490 10 l. 470 16 2.992 l 1. 465 20- 900 12 2. 990 24 2 Flat The tensioning pull on thestrip 1 causes the floating rolls [3 and [5 to automatically adjusttheir positions to equalize the tension on the strip and control thedirection of the strip between the fixed rolls adjacent thereto, andwhen the rolls l2 and I6 are adjusted by means of screws .2?

center of a. center stretched strip andvisibly' and audibly noting thesnap occurring .in. the strip.

- With the present improved method and appa- I ratus, we have found thatmetallic strip which has been coated; such as .for example galvanized,

- tin coated, terne coated, and painted strip steel,

can be satisfactorily center stretched. This due to the fact that thestretching is done entirely by rolling -contact, whereas any priorcenter stretching methods and apparatus'of which we are aware cause adragon the coating and produce scratches and the like on the surface ofthe strip.

The novel method and apparatus of the present invention provides a noveland economical 'method of producing longitudinally center stretchedstrip which is free from surface scratches, without requiring the use ofdrawing dies, such strip after being subsequently laterally curvedhaving sufiicient stiffness and rigidity to maintain itselfinlongitudinally straight condition and to restore itself or snap backto such condition when flexed. i

We claim: 1. Apparatus for center stretching a strip longitudinallythereof including a frame having laterally spaced side plates, a seriesof irregularly staggered convex rolls journal'ed at their ends in saidside plates, means for pulling a' continuous strip in a sinuous pathsuccessively past said rolls with its upper surface in contact with cer-.t-ain of said rolls and with its lower surface in.

- contact with others of said rolls, ;and floating and 38 respectively,the floating rolls l3 and i5 will change their positions accordinglyunder the tension on the strip to equalize the tension on the stripbetween the next preceding and following rolls, that is', floating rolll3 equalizes the tension between fixed rolls [2 and i l, and floatingroll l5 equalizes the tension between fixed rolls Id and I5.

Accordingto the present invention, thin metal strip having thedesiredamount of center stretch and after being subsequently laterally.curved, having the corresponding snap back and stiffeningcharacteristics, has been produced in actual.

practice by pulling the same through the novel apparatus shown and inthe manner described herein.

The degree of convex curvature of the various rolls in combination withthe amount of wrapping around the peripheries of certain of the rollsdue to their relative sizes and locations is largely responsible forproducing the required amount of center stretclnng in the strip. Thisamount of center stretching can be varied by adjusting the location ofthe adjustable rolls l2 or it and by varying the size or degree ofconvex curvature of one or more of the rolls.

Moreover, an increment of the stretch occurs in each strip portionextending between each successive pair of rolls, and particularlybetween rolls l2 and i3, i5 and i5, and i5 and it, s e

strip is being pulled past and in contact with the rolls under tension.Also an increment of the total center stretch occurs in the portion ofthe strip which is in contact with each roll and particularly at rollsl2, i3, i5 and iii. The sum' or total of these stretch increments equalsthe total amount .of center stretch imparted to the strip.

As the total amount of center stretch is a minute quantity and difiicultto measure, no exact value of the same can be stated. However, itsexistence in the strip is evident by pressing the mountings in said sideplates for certain of said rolls whereby-the tensioned pull on the stripadjusts the location of saidfioating rolls with ,respect to thenon-floating rolls to control the direction and equalize the'tension onthe strip between said non-floating rolls. 1

2. Apparatus for center-stretching 'a strip longitudinallyv thereofincluding a frame having laterally spaced side plates, a series ofirregularlystaggered convex rolls journaled at their ends in said sideplates, means for pulling a continuous strip in a sinuous pathsuccessively past said rolls with itsupper surface in contact withcertain of said rolls and with its lower surface in contactwith'othersof said rolls, certain of said rolls being so located with respect toothers of said rolls as to cause the strip to wrap around a substantialportion of at least one roll'tc substantially reverse the direction ofthepath of the strip at said one roll, and floating mountings in saidside plates for certain of said rolls wherebythe tensioned pull on thestrip adjusts the location of said floating rolls with respect to thenon floating rolls to control the direction and equalize the tension onthe strip between said.

non-floating rolls.

3. Apparatus fo center stretching a strip longitudinally thereofincluding a frame having laterally spaced side plates, a series ofirregularly staggered convex rolls journaled at their ends in said sideplates, means for pulling a continuous strip in a sinuous pathsuccessively pastsaid roll-s with its upper surface in contactwith'certain of said rolls and with its lower surface in contact withothers of said. rolls, certain of saidrolls being so located withrespect to iothers of said rollsas to cause the strip to'wrap its uppersurface around one of said rolls to substantially reversethe directionof the path of the strip .at said one roll, and to wrap its lowersurface around another of said rolls to substantially reverse thedirection of the path of the strip at said other roll, and floatingmountings -in said side plates for certain of said rolls whereby thetensioned pull on the strip adjusts the location of said floating rollswith respect to the non-floating rolls to control the direction andequalize the tension on the strip between said non-floating rolls.

4. Apparatus for center stretching a strip longitudinally thereofincluding a-frarne, a series of convex rolls journaledin said'frame,means for pulling a strip past and in. contact with one after another ofsaid rolls, said series of rolls including a first roll for engaging theupper surface of said strip, a second roll journaled above and forwardlyof said first roll for engaging the lower surface or said strip, a thirdroll spaced below said second rollfor engaging the upper. surface ofsaid strip and directing the strip down- 'ward1y,and* rearwardly fromsaid second roll,

means providing a vertically floating journal mounting for said thirdroll, a fourth roll jourstrip downwardly and forwardly.

vertically floating journal mounting ,for said second roll,a third rollspaced above and forwardly of aid second roll for engaging the lowersurface of said strip and directing the strip upwardly, means providinga horizontally floating mounting for said third roll, and a fourth rolljournaled forwardly of said third roll for engaging the upper surface ofsaid strip and directing it downwardly from said third roll.

'7. Apparatus for center stretching a strip longitudinally thereofincluding a frame, a series of convex rollsljournaled in said frame,means for pulling a strip past and in contact with one after another ofsaid rolls, said series of rolls including a roll having a maximumdiameter of 1.47 and a radius of convex curvature of, 16 for engagingthe lower surface of said strip, a second roll said strip and directingthe strip downwardly 5. Apparatus for center stretching a striplongitudinallythereof including a frame, a series "of convex rollsjournaled in said frame, means for pulling a strip past and in contactwith one after a first roll having a maximum diameter of 1.49"

and rearwardly from said first roll, means providing a verticallyfloating journal mounting for providing a horizontally floating journalmounting for said third roll, and a fourth rollhaving a maximum diameterof 2.990" and a radius of convex curvature of 24" journaled forwardly ofsaid third roll for engaging the upper surface of said strip anddirecting it downwardly from another of said rolls, said series of rollsincluding and a radius of convex curvature of for en gaging the uppersurface .of said strip, a second roll havinga maximum diameter of 1.47"and a maximum diameter" of 2.992" anda radius of convex curvature of 10"spaced below said second "roll for engagingjhe upper surface of saidstrip and directing the strip downwardly and rear- .wardly from aidsecond roll, means'providing a vertically floating journal mounting forsaid third roll, 'a fourth roll having a maximum ture of. 20 jogirn'aledforwardly-of said third roll for engaging the upper surface of saidstrip, a

fifth roll having a maximum diameter of .900 and a radius of convexcurvature of 12" spaced above and rearwardly of said fourth roll forengaging the lower surface of said strip and directing the stripupwardly and rearwardly from said fourth roll, means providing ahorizontally floating journal mounting for said fifth roll, and

a sixth roll having a maximum diameter of 2.990" and a radius of convexcurvature of 24" spaced forwardly of said fifth rollfor engaging theupper surface of 'said strip and directing the strip downwardly andforwardly,

' -6. Apparatus for center stretching a strip .longitudinally thereofincluding a frame, a series of convex rolls-journaled in said frame,means for pullinga strip past 'andin contact with one after another ofsaid rolls, said series of rolls including a roll for engaging the lowersurface of said strip, a second roll spacedbelow said first roll forengaging the upper surface of said strip and .directingthe stripdownwardly and rearwardly from said first roll, means providing a saidthird roll. 1 1

8. The method of continuously longitudinally center stretching a-stripto impart a permanent longitudinal center stretchtherein, which includescontinuousi klooping the strip under tension substantially pon itself inalternately opposite directions,, maintaining 'the strip laterallycurved as it is being looped, andyieldingly dediameter of 1.465"'and aradius of convex curva-" .flecting the path of the strip between saidloops' to equalize the tension on the strip between said loops and tolongitudinally stretch the center of the strip.

9. The method of continuously longitudinally jcenter stretchinga stripto impart a longitudinal center stretch therein, which includescontinuously looping the strip under tension alternately insubstantially opposite directions while maintaining thestrip laterallycurved, and yieldingly deflecting the path of the strip between saidwith certain of said rolls and with its lower surface in contact withothers of said rolls, and floating mountings in said frame for certainof said rolls whereby the tensioned pull on the strip adjusts thelocation of said floating rolls with respect to the non-floating 'rollsto control the direction and equalize the tension on the strip betweensaid non-floating rolls.

LLOYD W. WILSON; HAROLD W; LOWMILLER. MAXWELL L. BIBLE.

